The line comes from Whitest Kids U' Know, the American sketch comedy troupe whose television series aired on IFC. The tags point to their recurring Abraham Lincoln sketch, where the deadpan 'that's it' lands as a final ruling. Like many short WKUK quotes, it was ripped for soundboards and reaction edits, spreading through meme compilations and gaming clips. Editors still reach for it for the same reason they use the Bruh meme or the FAIL SOUND MEME, a two-second verdict that ends a bit without needing an explanation.